Technical Field
The present disclosure relates to a battery material and a method for manufacturing the same. More particularly, the present disclosure relates to an electrode material of a lithium ion battery and a method for manufacturing the same.
Description of Related Art
In recent years, with the development of 3C electronics, lightweight, mobile and high-energy batteries have attracted considerable attention. Among the high-energy batteries, lithium ion batteries have developed most maturely and been widely applied to portable electronics. For example, a smart phone evolves not only toward large size color screen, but also with more and more complicated functionalities of photo shooting and music playing. As a result, a demand for lightweight high-energy batteries is increasing. How to increase a capacity and a cycle life of the lithium ion batteries has become an important subject.
In the known technical solutions, a commonly used negative electrode material of the lithium ion batteries is a graphite-based material, such as a graphite carbon material. The graphite-based material has an excellent charge and discharge capacity, and no dendritic structure is generated, so that the graphite-based material is safer in performance. However, the structure of the negative electrode made of graphite-based material is spoiled due to the reversibly insertion and detachment of lithium ions after a number of charging and discharging cycles. Accordingly, the cycle life of the lithium ion batteries is influenced. Furthermore, a theoretical charge capacity of graphite is only about 372 mAh/g, and the development of the lithium ion batteries is limited thereby.
A lot of researches for improving the negative electrode material of the lithium ion batteries have been provided. For example, silicon material is mixed into the negative electrode of the lithium ion batteries. A theoretical capacity of the silicon material is about 4200 mAh/g, which is the highest among the materials applied to the negative electrode of the lithium ion batteries. However, a phase change is caused by the reversibly insertion and detachment of lithium ions, and a volume expansion is generated thereby. The volume expansion is so large that the cycling stability and irreversibility of the silicon-containing negative electrode of the lithium ion batteries are seriously influenced.
Minimizing the particle sizes of the silicon material is one of the solutions for controlling the volume expansion. For example, the particle sizes of the silicon material are minimized to the range of 10˜300 nm. Although it is common to control the volume expansion by minimizing the particle sizes of the silicon material to the nanoscale. The silicon material in the form of nanoscale particles is very expensive. Also, a significant irreversible capacity is caused due to a larger surface area of the nanoscale particles. Importantly, the nanoscale particles with similar sizes and shapes tend to aggregate with each other to form larger particles, and the process of uniformly mixing the materials to form the negative electrode becomes more difficult.
A columnar silicon material for reducing the volume expansion is disclosed. The particle sizes of the columnar silicon material are in a range of 10 μm to 800 μm. The columnar silicon material is formed by a chemical method including an etching step and a nucleating step. However, the formed columnar silicon material has to be removed from a substrate, such that the chemical method has a high cost and low manufacturing rate. Furthermore, the particle sizes of the columnar silicon material are limited by the chemical method, and the consistency of the sizes of the columnar silicon material intensifies the aggregation of the columnar silicon material. Therefore, a subsequent dispersion process is required for the columnar silicon material.
Given the above, how to obtain an environmental friendly silicon material, which is low cost and the volume expansion thereof can be well controlled, has become the important subject for the relevant industry of the lithium ion batteries.